Question

Tìm x thuộc Q, biết rằng:

    a) (x- 1/2)^2 =0                                                

    b) (x - 2)^2 = 1

    c) (2x - 1)^3 = -8

    d) (x +1/2)^2 = 1/16

Answer 1

a) ( x - 1/2 )² = 0

<=> x - 1/2 = 0

<=> x = 1/2

b) ( x - 2 )² = 1

<=> x - 2 = { 1; -1 }

<=> x = { 3; 1 }

c) ( 2x - 1 )³ = -8 = ( -2 )³

<=> 2x - 1 = -2

<=> 2x = -1

<=> x = -1/2

d) ( x + 1/2 )² = 1/16 

<=> x + 1/2 = { 1/4; -1/4 }

<=> x = { -1/4; -3/4 }

Answer 2

a.

(x-1/2)^2=0\(\Rightarrow\)x-1/2=0\(\Rightarrow\)x=1/2

b

(x-2)^2=1\(\Rightarrow\)x-2\(\in\){1;-1}

\(\Rightarrow\)x\(\in\){3;1}

c

(2x-1)^3=-8\(\Rightarrow\)2x-1=-2

\(\Rightarrow\)2x=-1

\(\Rightarrow\)x=-1/2

d

(x+1/2)^2=1/16\(\Rightarrow\)x+1/2\(\in\){1/4;-1/4}

\(\Rightarrow\)x\(\in\){-1/4;-3/4}

Answer 3

bai nay tuy kho nhunh doi voi minh thi biet thua de nhu an banh vay